Blockchain Security Training Network and Node Security 2

Question 1

An attacker monopolizes all of a victim node's peer connections to control its view of the network. What attack is this?

Accepted Answer

Eclipse attack

Answer

An eclipse attack isolates a node by occupying all its inbound and outbound connections so the attacker controls everything it sees.

Question 2

Which practice best protects a validator node's signing keys?

Accepted Answer

Store keys in a hardware security module or remote signer

Answer

Isolating signing keys in an HSM or remote signer keeps them off the internet-facing node and limits exposure.

Question 3

What is the primary purpose of running a node behind a firewall that only exposes the P2P port?

Accepted Answer

Reduce attack surface by blocking unneeded ports

Answer

Limiting open ports to only what the node needs shrinks the attack surface available to remote adversaries.

Question 4

A node operator notices the RPC interface is reachable from the public internet. What is the main risk?

Accepted Answer

Unauthorized access to node management and wallet functions

Answer

Exposed RPC endpoints can let attackers query or control the node and potentially drain hot wallets.

Question 5

Which DNS-related weakness can mislead a new node during initial peer discovery?

Accepted Answer

Poisoned DNS seed returning attacker-controlled peers

Answer

If DNS seeds are poisoned, a bootstrapping node may connect only to malicious peers, enabling eclipse-style isolation.

Blockchain Practice Test